Memory devices (e.g., integrated circuits) can include memory elements formed above a device substrate. Such memory elements can be considered “back end of line” (BEOL) elements as they can be formed after active devices (e.g., transistors) have been formed on, or in conjunction with, a substrate. Formation of devices such as transistors is often considered “the front end of line”.
Various types of memory elements can be BEOL elements, including but not limited to: conductive bridging random access memory (CBRAM, also referred to as programmable metallization (PMC)) elements, phase change memory elements, ferroelectric memory elements, and magnetoresistive memory elements.
Conventionally, structures within BEOL type memory element structures can be limited by minimum feature sizes achievable by BEOL processes.
FIG. 16 shows a conventional CBRAM type memory element 1600. Conventional element 1600 includes an ion conducting material 1603 formed between an anode electrode 1601 and a cathode electrode 1605. An ion conducting material 1603 includes an ion conducting matrix with an oxidizable metal formed therein. In response to the application of a voltage that is positive at the anode electrode 1601 with respect to the cathode electrode 1605, a conductive path can be formed between the electrodes, reducing a resistance of the element 1600. In response to the application of a voltage that is negative at the anode electrode 1601 with respect to the cathode electrode 1605, such a conductive path can dissolve, returning the element 1600 to a higher resistance state.
In element 1600, anode and cathode electrodes (1601/1603), as well as ion conducting material 1603 can be localized to an opening 1607. Such an opening 1607 can have a minimum width of “F”, where F is a minimum lithographic feature size.